Question

Which of the following metal do no evolve $H_2$ gas from dil. acid?

• A. $A(E_{A^{+}/A}^o=0.25V)$
• B. $B(E_{B/B^{+}}^0=+0.22V)$
• C. $C(E_{C^{+}/C}^0=0.30V)$
• D. $D(E_{D/D^{+}}^0=+0.44V)$

Answer 1

The correct option is A $A(E_{A^{+}/A}^o=0.25V)$

• If the standard electrode potential of an electrode is greater than zero then its reduced form is more stable compared to hydrogen gas.
  
• Similarly, if the standard electrode potential is negative then hydrogen gas is more stable than the reduced form of the species.
  
• Here the standard electrode potential is reduction potential and hence option A doesn't give $H_2$ gas when reacted with dilute acid.